Book Image

R Data Structures and Algorithms

By : PKS Prakash, Achyutuni Sri Krishna Rao
Book Image

R Data Structures and Algorithms

By: PKS Prakash, Achyutuni Sri Krishna Rao

Overview of this book

In this book, we cover not only classical data structures, but also functional data structures. We begin by answering the fundamental question: why data structures? We then move on to cover the relationship between data structures and algorithms, followed by an analysis and evaluation of algorithms. We introduce the fundamentals of data structures, such as lists, stacks, queues, and dictionaries, using real-world examples. We also cover topics such as indexing, sorting, and searching in depth. Later on, you will be exposed to advanced topics such as graph data structures, dynamic programming, and randomized algorithms. You will come to appreciate the intricacies of high performance and scalable programming using R. We also cover special R data structures such as vectors, data frames, and atomic vectors. With this easy-to-read book, you will be able to understand the power of linked lists, double linked lists, and circular linked lists. We will also explore the application of binary search and will go in depth into sorting algorithms such as bubble sort, selection sort, insertion sort, and merge sort.
Table of Contents (17 chapters)
R Data Structures and Algorithms
Credits
About the Authors
Acknowledgments
About the Reviewer
www.PacktPub.com
Preface

ISAM


ISAM, promoted by IBM and Ingres DBMS, also uses the linear indexing philosophy of primary key sorting. In ISAM, files on disk are divided into cylinders on disk. The cylinders are tracks readable from a particular placement of the head on a multiple platter of disk drive. ISAM addresses the limitation of linear indexing of insertion or deletion to some extent due to its static structure, but it is only suitable for small changes. Thus, ISAM is usually applied in databases which are not frequently updated. Static index allocation makes frequent insertion and deletion an expensive process. However, it helps with concurrent access of records, which helps to scale the efficiency of the current data structure. The drawbacks of ISAM with regard to insertion/deletion was later addressed by B-tree based indexing. The ISAM approach was used before the adoption of tree-based indexing:

Figure 7.5: Illustration of ISAM structure

The ISAM data structure consists of a memory-resident cylinder index...